Semiconductor device and semiconductor memory device

ABSTRACT

Semiconductor device and semiconductor memory device include a plurality of internal circuits configured to perform test operations in response to their respective test mode signals and a plurality of test-off units configured to control the test operations of the internal circuits to be disabled in response to a test-off signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority of Korean patent application number 10-2007-0111351, filed on Nov. 2, 2007, which is incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device and a semiconductor memory device, and more particularly, to technology for preventing a semiconductor device from malfunctioning due to a coupling phenomenon that occurs in lines through which test mode signals are transmitted.

With the development of technology, the process of fabricating a semiconductor memory device has gradually improved so as to enable the production of such devices with elements of smaller and smaller size, thus to achieve higher capacity.

With these improvements in the fabrication process, chip sizes have decreased, allowing or requiring more and more metal lines to be disposed in a small space. As more and more metal lines are disposed in a smaller space, the influence of a capacitive coupling effect (i.e., such an effect as if capacitors are present between the metal lines) increases. A variety of signals and data are affected by noise due to such coupling capacitors, and there is therefore an increasing need to reduce this effect.

FIG. 1 is a diagram illustrating that transmission lines for test mode signals are disposed between global data input/output (I/O) lines in order to reduce a coupling effect between the global data I/O lines.

Referring to FIG. 1, when toggle signal lines such as global data I/O lines GIO1, GIO2 and GIO3 are disposed adjacent to each other, they are greatly affected by interference due to a coupling effect. Thus, supply voltage (VDD) lines (not illustrated in FIG. 1) or ground voltage (VSS) lines (not illustrated in FIG. 1) are disposed between the global data I/O lines GIO1, GIO2 and GIO3 in order to prevent or reduce a coupling effect between the global data I/O lines GIO1, GIO2 and GIO3.

However, since power lines such as VDD lines or VSS lines are limited in number, it is impossible to dispose a sufficient number of power lines between the global data I/O lines GIO1, GIO2 and GIO3. Thus, as illustrated in FIG. 1, transmission lines for DC signals such as test mode signals TM_A and TM_B are disposed between the global data I/O lines GIO1, GIO2 and GIO3.

As is well known in the art, the test mode signals TM_A and TM_B are level signals. In general, the test mode signals TM_A and TM_B must be at a ‘High’ level in a test mode and must be at a ‘Low’ level in a non-test mode. Thus, in designing a memory device, the transmission lines for the test mode signals TM_A and TM_B having the same level as the ground voltage (VSS) are disposed between the global data I/O lines GIO1, GIO2 and GIO3 in the normal case of the non-test mode in order to prevent a coupling effect between the global data I/O lines GIO1, GIO2 and GIO3.

FIG. 2 is a diagram illustrating a problem that occurs when the transmission lines for the test mode signals TM_A and TM_B are disposed between the global data I/O lines GIO1, GIO2 and GIO3.

Referring to FIG. 2, when data of the global data I/O lines GIO1, GIO2 and GIO3 around the transmission lines for the test mode signals TM_A and TM_B change from ‘Low’ to ‘High’ level, the test mode signals TM_A and TM_B also change from ‘Low’ to ‘High’ level due to a coupling effect between the global data I/O lines GIO1, GIO2 and GIO3. Thus, internal circuits receiving the test mode signals TM_A and TM_B enter into a test mode unintentionally.

The internal circuits receiving the test mode signals TM_A and TM_B have a test mode and a normal mode (i.e., a normal operation mode not being the test mode). Prescribed normal operations are performed in the normal mode, whereas operations other than the normal operations are performed in the test mode with a change in an operation frequency or a voltage level. Thus, when the internal circuits enter into the test mode due to the coupling effect during a normal operation, the memory device cannot perform the normal operation, which causes a failure in data read/write operations.

FIG. 3 is a diagram illustrating another problem that occurs when the transmission lines for the test mode signals TM_A and TM_B are disposed between the global data I/O lines GIO1, GIO2 and GIO3.

Referring to FIG. 3, there is a case where the data of the global data I/O lines GIO1, GIO2 and GIO3 rise to a ‘High’ level at the time when the internal circuits must escape from the test mode when the test mode signals TM_A and TM_B drop to a ‘Low’ level. In this case, the test mode signals TM_A and TM_B drop from a ‘High’ level slightly, rise toward the ‘High’ level again, and then drop toward the ‘Low’ level. Thus, a delay time is taken for the test mode signals TM_A and TM_B to drop from the ‘High’ level to the ‘Low’ level. This delay time changes the entry time from the test mode into the normal mode, thus causing another malfunction.

As described above, when the transmission lines for the test mode signals TM_A and TM_B are disposed between the global data I/O lines GIO1, GIO2 and GIO3, it is possible to reduce the coupling effect between the global data I/O lines GIO1, GIO2 and GIO3. However, the memory device may malfunction due to an unintentional entry into the test mode or a change in the entry time into the normal mode.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to providing semiconductor memory devices and semiconductor devices that can operate stably even when test mode signals are affected by a coupling effect that occurs due to, for example, the arrangement of lines.

In accordance with an aspect of the invention, internal circuits are configured to perform test operations in response to their respective test mode signals and test-off units are configured to control the test operations of the internal circuits to be disabled in response to a test-off signal.

In accordance with another aspect of the invention, transmission lines are disposed between data input/output lines to transmit test mode signals, internal circuits are configured to perform test operations in response to the corresponding test mode signals received through the transmission lines, an off-signal transmission line is disposed to be less affected by a coupling effect than the transmission lines disposed between the input/output lines, that is, signals induced therein due to coupling by parasitic capacitance would tend to be smaller in magnitude than signals that would be induced in the transmission lines, and test-off units are configured to control the test operations of the internal circuits to be disabled in response to a test-off signal received through the off-signal transmission line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating that transmission lines for test mode signals are disposed between global data I/O lines in order to reduce a coupling effect between the global data I/O lines.

FIG. 2 is a diagram illustrating a problem that occurs when transmission lines for test mode signals TM_A and TM_B are disposed between global data I/O lines GIO1, GIO2 and GIO3.

FIG. 3 is a diagram illustrating another problem that occurs when the transmission lines for the test mode signals TM_A and TM_B are disposed between the global data I/O lines GIO1, GIO2 and GIO3.

FIG. 4 is a block diagram of a semiconductor memory device in accordance with an embodiment of the present invention.

FIG. 5 is a diagram illustrating an effect that is obtained by activating a test-off signal TM_OFF in a normal operation.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Hereinafter, a semiconductor device and a semiconductor memory device in accordance with the present invention will be described in detail with reference to the accompanying drawings.

FIG. 4 is a block diagram of a semiconductor memory device in accordance with an embodiment of the invention.

Referring to FIG. 4, a semiconductor memory device in accordance with the invention includes internal circuits 410, 420 and 430 configured to perform test operations in response to their respective test mode signals TM_A, TM_B and TM_C; and test-off units 440, 450 and 460 configured to control the test operations of the internal circuits 410, 420 and 430 to be disabled in response to a (common) test-off signal TM_OFF.

The internal circuits 410, 420 and 430 mean various circuits in the semiconductor memory device. Examples of the internal circuits 410, 420 and 430 include an internal voltage generating circuit, a data input/output (I/O) circuit and a clock generating circuit. When the test mode signals TM_A, TM_B and TM_C are deactivated, the internal circuits 410, 420 and 430 perform normal operations. On the other hand, when the test mode signals TM_A, TM_B and TM_C are activated, the internal circuits 410, 420 and 430 enter into a test mode to perform operations other than the normal operations. For example, the internal circuits 410, 420 and 430 perform test operations, such as generating an internal voltage with a different level or operating at a different frequency than in the normal operations.

When the test-off signal TM_OFF is activated, the test-off units 440, 450 and 460 disable the test operations of the internal circuits 410, 420 and 430 regardless of the logic levels of the test mode signals TM_A, TM_B and TM_C. That is, when the test-off signal TM_OFF is activated, the test mode signals TM_A, TM_B and TM_C are deactivated and input to the internal circuits 410, 420 and 430 to deactivate the test operations of the internal circuits 410, 420 and 430. Thus, it is preferable that the test-off units 440, 450 and 460 are respectively disposed adjacent to the internal circuits 410, 420 and 430.

As illustrated in FIG. 4, the test-off unit 440 may include a NOR gate 441 for NORing the test-off signal TM_OFF and the test mode signal TM_A, the test-off unit 450 may include a NOR gate 451 for NORing the test-off signal TM_OFF and the test mode signal TM_B, and the test-off unit 460 may include a NOR gate 461 for NORing the test-off signal TM_OFF and the test mode signal TM_C. When the test-off signal TM_OFF is deactivated, the NOR gates 441, 451 and 461 respectively output the test mode signals TM_A, TM_B and TM_C as they are. On the other hand, when the test-off signal TM_OFF is activated, the NOR gates 441, 451 and 461 output logic ‘Low’ signals regardless of the logic levels of the test mode signals TM_A, TM_B and TM_C, thereby changing the internal circuits 410, 420 and 430 into a normal mode state.

As illustrated in FIG. 4, since the test mode signals TM_A TM_B and TM_C are transmitted respectively through transmission lines 471, 472 and 473 disposed between global data I/O lines GIO1, GIO2, GIO3 and GIO4, the test mode signals TM_A, TM_B and TM_C are more affected by a coupling effect between the global data I/O lines GIO1, GIO2, GIO3 and GIO4. Herein, it is preferable that an off-signal transmission line 474 for transmitting the test-off signal TM_OFF is disposed to be less affected by the coupling effect. The reason for this is that the invention is characterized in that it prevents the internal circuits 410, 420 and 430 from entering into the test mode according to the test-off signal TM_OFF even when the test mode signals TM_A, TM_B and TM_C are affected by the coupling effect. This is possible by disposing the off-signal transmission line 474, through which the test-off signal TM_OFF is transmitted, to be distant from other transmission lines that may affect the coupling effect.

Thus, the use of the technology of the invention makes it possible for a designer of the semiconductor memory device to less consider the coupling effect on the transmission lines 471, 472 and 473 for the test mode signals TM_A, TM_B and TM_C. That is, the designer has only to consider the coupling effect on the off-signal transmission line 474 (i.e., the transmission line for the test-off signal TM_OFF) in order to design the semiconductor memory device.

The semiconductor memory device may be designed such that the test-off signal TM_OFF is externally received from the outside of a chip of the semiconductor memory device. Alternatively, the test-off signal TM_OFF may be generated by MRS setting or depending on whether a fuse in a fuse circuit is cut. Any one skilled in the art can design to generate or input the test-off signal TM_OFF, and thus its detailed description will be omitted for conciseness.

The above-described embodiment and the drawings have illustrated the case where the technology of the invention is applied to a semiconductor memory device. However, the invention can be applied not only to a semiconductor memory device but also to a general semiconductor device. The reason for this is that a general semiconductor device also has a test mode thereof and a coupling problem of a test mode signal for controlling the test mode may be problematic in all the semiconductor devices that are fabricated through a fine process.

A semiconductor device in accordance with the invention may include transmission lines (corresponding to the reference numerals 471, 472 and 473 in FIG. 4) that are more affected by a coupling effect; internal circuits (corresponding to the reference numerals 410, 420 and 430 in FIG. 4) that perform test operations in response to their respective test mode signals (corresponding to the reference symbols TM_A, TM_B and TM_C in FIG. 4) among the test mode signals received through the transmission lines; an off-signal transmission line (corresponding to the reference numeral 474 in FIG. 4) that is disposed to be less affected by the coupling effect; and test-off units (corresponding to the reference numerals 440, 450 and 460 in FIG. 4) that controls the test operations of the internal circuits to be disabled in response to a test-off signal (corresponding to the reference symbol TM_OFF in FIG. 4) that is received through the off-signal transmission line.

In the same manner as in the semiconductor memory device, when the test-off signal is deactivated, the internal circuits always maintain a normal mode regardless of the logic levels of the test mode signals. Thus, even when the logic levels of the test mode signals change due to the coupling effect, the internal circuits do not generate a malfunction of entering into the test mode during the normal operation. Of course, the test-off units may be configured in the same way as the test-off units 440, 450 and 460 illustrated in FIG. 4.

By using the test-off signal (TM_OFF), the semiconductor device in accordance with the invention has the advantage that its designer has only to consider, in its designing stage, the coupling effect on the off-signal transmission line (e.g., to dispose the off-signal transmission line to be distant from, for example, a clock transmission line that may case the coupling effect) while less considering the coupling effect on the transmission lines for the test mode signals (TM_A, TM_B and TM_C). The basic principle applied to the semiconductor memory device can also be applied to the general semiconductor device, and thus its detailed description will be omitted for conciseness.

FIG. 5 is a diagram illustrating an effect that is obtained by activating the test-off signal TM_OFF in the normal operation.

As illustrated in FIG. 5, when the test-off signal TM_OFF is activated in the normal operation, the output nodes (node A, node B and node C) of the test-off units 440, 450 and 460 always maintain a logic ‘Low’ level even when the logic levels of the test mode signals TM_A, TM_B and TM_C fluctuate due to the coupling effect. Thus, the internal circuits 410, 420 and 430 do not generate a malfunction of entering into the test mode due to the coupling effect during the normal operation.

That is, the invention activates the test-off signal TM_OFF during the normal operation, thereby making it possible to prevent the internal circuits 410, 420 and 430 from malfunctioning due to the coupling effect.

As described above, the invention activates the test-off signal during the normal operation, thereby enabling the internal circuits to perform a normal operation regardless of the logic levels of the test mode signals without entering into the test mode.

Therefore, the internal circuits of the semiconductor device can perform a stable operation without entering into the test mode even when the logic levels of the test mode signals change due to, for example, the coupling effect and the noise effect.

While the invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. 

1. A semiconductor memory device, comprising a plurality of internal circuits configured to perform test operations in response to respective test mode signals, and a plurality of test-off units configured to disable the test operations of the internal circuits in response to a test-off signal.
 2. The semiconductor memory device as recited in claim 1, wherein when the test-off signal is activated, the test-off units disable the test operations of the internal circuits regardless of the logic levels of the test mode signals.
 3. The semiconductor memory device as recited in claim 1, wherein when the test-off signal is activated, the test-off units deactivate the test mode signals and output the deactivated test mode signals to corresponding internal circuits.
 4. The semiconductor memory device as recited in claim 3, wherein the test-off units are adjacent respectively to corresponding internal circuits such that the test-off units control the corresponding internal circuits.
 5. The semiconductor memory device as recited in claim 3, wherein each of the test-off units includes a NOR gate for NORing the test-off signal and a corresponding one of the test mode signals for a corresponding one of the internal circuits.
 6. The semiconductor memory device as recited in claim 1, wherein the test mode signals are transmitted through first lines that are more affected by a coupling effect than a second line, and the test-off signal is transmitted through the second line that is less affected by the coupling effect than the first lines.
 7. The semiconductor memory device as recited in claim 1, wherein the test-off signal is activated in a normal operation to prevent the test operations of the internal circuits.
 8. A semiconductor memory device, comprising: a plurality of transmission lines disposed between data input/output lines to transmit a plurality of test mode signals; a plurality of internal circuits configured to perform test operations in response to the corresponding test mode signals received through the transmission lines; an off-signal transmission line disposed to be less affected by a coupling effect than each of said plurality of transmission lines; and a plurality of test-off units configured to disable the test operations of the internal circuits in response to a test-off signal received through the off-signal transmission line.
 9. The semiconductor memory device as recited in claim 8, wherein when the test-off signal is activated, the test-off units disable the test operations of the internal circuits regardless of the logic levels of the test mode signals.
 10. The semiconductor memory device as recited in claim 8, wherein when the test-off signal is activated, the test-off units deactivate the test mode signals and output the deactivated test mode signals to corresponding internal circuits.
 11. The semiconductor memory device as recited in claim 10, wherein each of the test-off units includes a NOR gate for NORing the test-off signal and a corresponding one of the test mode signals for a corresponding one of the internal circuits.
 12. The semiconductor memory device as recited in claim 8, wherein the test-off signal is activated in a normal operation to prevent the test operations of the internal circuits.
 13. A semiconductor device, comprising: a plurality of first transmission lines disposed to be more affected by a coupling effect; a plurality of internal circuits configured to perform test operations in response to corresponding test mode signals received through the first transmission lines; an off-signal second transmission line disposed to be less affected by the coupling effect than the first transmission lines; and a plurality of test-off units configured to control the test operations of the internal circuits to be disabled in response to a test-off signal received through the second off-signal transmission line.
 14. The semiconductor device as recited in claim 13, wherein when the test-off signal is activated, the test-off units disable the test operations of the internal circuits regardless of the logic levels of the test mode signals.
 15. The semiconductor device as recited in claim 13, wherein when the test-off signal is activated, the test-off units deactivate the test mode signals and output the deactivated test mode signals to corresponding internal circuits.
 16. The semiconductor device as recited in claim 13, wherein the test-off signal is activated in a normal operation to prevent the test operations of the internal circuits. 